This invention relates to an apparatus and method for maximizing heat transfer in both upstream and downstream fin enhancements of a heat exchanger fin.
Finned heat exchanger coil assemblies are widely used in a number of applications in fields such as air conditioning and refrigeration. A finned heat exchanger coil assembly generally includes a plurality of spaced parallel tubes through which a heat transfer fluid such as water or refrigerant flows. A second heat transfer fluid, usually air, is directed across the tubes. A plurality of fins is usually employed to improve the heat transfer capabilities of the heat exchanger coil assembly. Each fin is a thin metal plate, made of copper or aluminum, which may or may not include a hydrophilic coating. Each fin includes a plurality of apertures for receiving the spaced parallel tubes, such that the tubes generally pass through the plurality of fins at right angles to the fins. The fins are arranged in a parallel, closely-spaced relationship along the tubes to form multiple paths for the air or other heat transfer fluid to flow across the fins and around the tubes.
Often the fin includes one or more enhancements to improve the efficiency of heat transfer. For example, many prior art heat exchanger fins include a smooth enhancement, such as a corrugated or sinusoid-like shape when viewed in cross-section. In addition, or instead of, the smooth enhancement, heat exchanger fins may also include enhancements such as lances or louvers. Such enhancements are formed out of a stock line (the plane of the fin material out of which all fin features are formed). Usually, such enhancements are symmetrical, with reference to any point along the path of air passing over the fin such that enhanced fins include both upstream and downstream enhancements.
Unfortunately, the upstream and downstream lances are often formed at the same angle with respect to the stock line. This results in downstream lances which are in the wake of the upstream lances, inhibiting the effective heat transfer between the downstream lances and the air. Additionally, overlapped louvers have the same problem, that is, heat transfer performance of downstream louvers is adversely affected by upstream louvers.
Thus, there is a need to provide an enhancement which maximizes effective heat transfer of both upstream and downstream lances.
According to one aspect of the present invention, a heat exchanger coil assembly is provided. The assembly comprises a plurality of fins arranged substantially in parallel with a direction of mean air flow, such that air can flow between adjacent fins, each fin having a plurality of cylindrical sleeves and a corrugated shape comprising at least two corrugations, each corrugation including a first lance and a second lance downstream of the first lance, wherein the first lance is canted at a first angle with respect to the mean air flow direction and the second lance is canted at a second angle with respect to the mean air flow direction, the first angle being different from the second angle such that when air flow passes over the fin, a wake of the first lance will not impinge upon the second lance, and a plurality of heat transfer tubes arranged substantially perpendicular to the plurality of fins, each tube passing through the cylindrical sleeves in the plurality of fins.
According to another aspect of the present Invention, a finned heat exchanger coil assembly is provided, wherein heat transfer takes place between a first fluid flowing through a plurality of spaced-apart finned heat transfer tubes and a second fluid flowing outside of the tubes, Each fin has a corrugated shape with at least two corrugations, each corrugation having a first lance and a second lance downstream of the first lance, wherein the first lance is canted at a first angle with respect to a direction of mean airflow and the second lance is canted at a second angle with respect to the direction of mean airflow, wherein the first angle is different from the second angle such that when air flow passes over the fin, a wake of the first lance will not Impinge upon the second lance.
According to a further aspect of the present invention, a finned heat exchanger coil assembly is provided, wherein heat transfer takes place between a first fluid flowing through a plurality of spaced-apart finned heat transfer tubes and a second fluid flowing outside of the tubes. Each fin comprises at least two corrugations, each corrugation having a first lance on an upstream side of the corrugation and a second lance on a downstream side of the corrugation, wherein the first lance forms an angle of between 5 and 15 degrees with respect to a direction of mean airflow, and wherein the second lance is parallel to the direction of mean airflow, such that a wake of the first lance will not impinge upon the second lance.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description, serve to explain the principles of the invention.